PhD defence Stefan Smedegaard Warthegau

Abstract

Modern society relies heavily on chemicals and materials produced from fossil resources such as oil and natural gas. However, continued dependence on these resources contributes to climate change and resource depletion. One promising alternative is to produce chemicals from renewable biomass, such as plant-derived sugars and agricultural residues. While biomass offers a sustainable carbon source, converting it into useful chemicals is far from straightforward. Biomass molecules are structurally complex and can follow many competing reaction pathways, often leading to unwanted byproducts. Controlling these reactions is therefore a major challenge in green chemistry.

A key step toward more sustainable chemical production is to understand in detail how these reactions proceed. In this PhD project, advanced spectroscopic techniques were used to “observe” chemical reactions as they happen. By applying specialized forms of nuclear magnetic resonance (NMR) spectroscopy, it was possible to monitor reaction progress in real time and detect short-lived intermediate species that are normally difficult to capture. This provides insight into why certain products form under specific conditions.

The research explored several complex reaction systems based on renewable carbon sources, with the aim of understanding how such transformations can be controlled. Across these studies, it was shown that factors such as solvent choice, acidity, catalyst type, and even subtle electrostatic effects can significantly influence which products are formed. Small changes in the reaction environment can redirect entire reaction pathways. By combining experimental measurements with kinetic modeling and chemical intuition, this thesis establishes a framework for understanding and controlling complex reaction networks based on renewable feedstocks. Such mechanistic insights are essential for designing more selective and efficient chemical processes.

Overall, this work contributes to the broader transition toward a sustainable chemical industry by strengthening the scientific foundation required to replace fossil-based production with renewable alternatives.

Principal Supervisor: 

Professor Sebastian Meier, DTU Chemistry

Co-supervisors: 

Associate Professor Pernille Rose Jensen, DTU Health Tech

Examiners:

Professor Charlotte Held Gotfredsen, DTU Chemistry
Professor Mogens Brøndsted Nielsen, University of Copenhagen
Professor Christian Hulteberg, Lund University

Chairperson: